freebsd-dev/sys/geom/geom_event.c
Alexander Motin 9794a803fd Retire nstart/nend counters.
Those counters were abused for decade to workaround broken orphanization
process in different classes by delaying the call while there are active
requests.  But from one side it did not close all the races, while from
another was quite expensive on SMP due to trashing twice per request cache
lines of consumer and provider and requiring locks.  It lost its sense
after I manually went through all the GEOM classes in base and made
orphanization wait for either provider close or request completion.

Consumer counters are still used under INVARIANTS to detect premature
consumer close and detach.  Provider counters are removed completely.

Sponsored by:	iXsystems, Inc.
2019-12-30 00:46:10 +00:00

445 lines
10 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2002 Poul-Henning Kamp
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Poul-Henning Kamp
* and NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* XXX: How do we in general know that objects referenced in events
* have not been destroyed before we get around to handle the event ?
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <geom/geom.h>
#include <geom/geom_int.h>
#include <machine/stdarg.h>
TAILQ_HEAD(event_tailq_head, g_event);
static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
static u_int g_pending_events;
static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
static struct mtx g_eventlock;
static int g_wither_work;
#define G_N_EVENTREFS 20
struct g_event {
TAILQ_ENTRY(g_event) events;
g_event_t *func;
void *arg;
int flag;
void *ref[G_N_EVENTREFS];
};
#define EV_DONE 0x80000
#define EV_WAKEUP 0x40000
#define EV_CANCELED 0x20000
#define EV_INPROGRESS 0x10000
void
g_waitidle(void)
{
g_topology_assert_not();
mtx_lock(&g_eventlock);
TSWAIT("GEOM events");
while (!TAILQ_EMPTY(&g_events))
msleep(&g_pending_events, &g_eventlock, PPAUSE,
"g_waitidle", hz/5);
TSUNWAIT("GEOM events");
mtx_unlock(&g_eventlock);
curthread->td_pflags &= ~TDP_GEOM;
}
#if 0
void
g_waitidlelock(void)
{
g_topology_assert();
mtx_lock(&g_eventlock);
while (!TAILQ_EMPTY(&g_events)) {
g_topology_unlock();
msleep(&g_pending_events, &g_eventlock, PPAUSE,
"g_waitidlel", hz/5);
g_topology_lock();
}
mtx_unlock(&g_eventlock);
}
#endif
struct g_attrchanged_args {
struct g_provider *pp;
const char *attr;
};
static void
g_attr_changed_event(void *arg, int flag)
{
struct g_attrchanged_args *args;
struct g_provider *pp;
struct g_consumer *cp;
struct g_consumer *next_cp;
args = arg;
pp = args->pp;
g_topology_assert();
if (flag != EV_CANCEL && g_shutdown == 0) {
/*
* Tell all consumers of the change.
*/
LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
if (cp->geom->attrchanged != NULL)
cp->geom->attrchanged(cp, args->attr);
}
}
g_free(args);
}
int
g_attr_changed(struct g_provider *pp, const char *attr, int flag)
{
struct g_attrchanged_args *args;
int error;
args = g_malloc(sizeof *args, flag);
if (args == NULL)
return (ENOMEM);
args->pp = pp;
args->attr = attr;
error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
if (error != 0)
g_free(args);
return (error);
}
void
g_orphan_provider(struct g_provider *pp, int error)
{
/* G_VALID_PROVIDER(pp) We likely lack topology lock */
g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
pp, pp->name, error);
KASSERT(error != 0,
("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
pp, pp->name));
pp->error = error;
mtx_lock(&g_eventlock);
KASSERT(!(pp->flags & G_PF_ORPHAN),
("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
pp->flags |= G_PF_ORPHAN;
TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
mtx_unlock(&g_eventlock);
wakeup(&g_wait_event);
}
/*
* This function is called once on each provider which the event handler
* finds on its g_doorstep.
*/
static void
g_orphan_register(struct g_provider *pp)
{
struct g_consumer *cp, *cp2;
int wf;
g_topology_assert();
G_VALID_PROVIDER(pp);
g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
g_cancel_event(pp);
wf = pp->flags & G_PF_WITHER;
pp->flags &= ~G_PF_WITHER;
/*
* Tell all consumers the bad news.
* Don't be surprised if they self-destruct.
*/
LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
KASSERT(cp->geom->orphan != NULL,
("geom %s has no orphan, class %s",
cp->geom->name, cp->geom->class->name));
/*
* XXX: g_dev_orphan method does deferred destroying
* and it is possible, that other event could already
* call the orphan method. Check consumer's flags to
* do not schedule it twice.
*/
if (cp->flags & G_CF_ORPHAN)
continue;
cp->flags |= G_CF_ORPHAN;
cp->geom->orphan(cp);
}
if (LIST_EMPTY(&pp->consumers) && wf)
g_destroy_provider(pp);
else
pp->flags |= wf;
#ifdef notyet
cp = LIST_FIRST(&pp->consumers);
if (cp != NULL)
return;
if (pp->geom->flags & G_GEOM_WITHER)
g_destroy_provider(pp);
#endif
}
static int
one_event(void)
{
struct g_event *ep;
struct g_provider *pp;
g_topology_assert();
mtx_lock(&g_eventlock);
pp = TAILQ_FIRST(&g_doorstep);
if (pp != NULL) {
G_VALID_PROVIDER(pp);
TAILQ_REMOVE(&g_doorstep, pp, orphan);
mtx_unlock(&g_eventlock);
g_orphan_register(pp);
return (1);
}
ep = TAILQ_FIRST(&g_events);
if (ep == NULL) {
wakeup(&g_pending_events);
return (0);
}
if (ep->flag & EV_INPROGRESS) {
mtx_unlock(&g_eventlock);
return (1);
}
ep->flag |= EV_INPROGRESS;
mtx_unlock(&g_eventlock);
g_topology_assert();
ep->func(ep->arg, 0);
g_topology_assert();
mtx_lock(&g_eventlock);
TSRELEASE("GEOM events");
TAILQ_REMOVE(&g_events, ep, events);
ep->flag &= ~EV_INPROGRESS;
if (ep->flag & EV_WAKEUP) {
ep->flag |= EV_DONE;
mtx_unlock(&g_eventlock);
wakeup(ep);
} else {
mtx_unlock(&g_eventlock);
g_free(ep);
}
return (1);
}
void
g_run_events()
{
for (;;) {
g_topology_lock();
while (one_event())
;
mtx_assert(&g_eventlock, MA_OWNED);
if (g_wither_work) {
g_wither_work = 0;
mtx_unlock(&g_eventlock);
g_wither_washer();
g_topology_unlock();
} else {
g_topology_unlock();
msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
"-", 0);
}
}
/* NOTREACHED */
}
void
g_cancel_event(void *ref)
{
struct g_event *ep, *epn;
struct g_provider *pp;
u_int n;
mtx_lock(&g_eventlock);
TAILQ_FOREACH(pp, &g_doorstep, orphan) {
if (pp != ref)
continue;
TAILQ_REMOVE(&g_doorstep, pp, orphan);
break;
}
TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
if (ep->flag & EV_INPROGRESS)
continue;
for (n = 0; n < G_N_EVENTREFS; n++) {
if (ep->ref[n] == NULL)
break;
if (ep->ref[n] != ref)
continue;
TSRELEASE("GEOM events");
TAILQ_REMOVE(&g_events, ep, events);
ep->func(ep->arg, EV_CANCEL);
mtx_assert(&g_eventlock, MA_OWNED);
if (ep->flag & EV_WAKEUP) {
ep->flag |= (EV_DONE|EV_CANCELED);
wakeup(ep);
} else {
g_free(ep);
}
break;
}
}
if (TAILQ_EMPTY(&g_events))
wakeup(&g_pending_events);
mtx_unlock(&g_eventlock);
}
static int
g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
{
struct g_event *ep;
void *p;
u_int n;
g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
func, arg, flag, wuflag);
KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
ep = g_malloc(sizeof *ep, flag | M_ZERO);
if (ep == NULL)
return (ENOMEM);
ep->flag = wuflag;
for (n = 0; n < G_N_EVENTREFS; n++) {
p = va_arg(ap, void *);
if (p == NULL)
break;
g_trace(G_T_TOPOLOGY, " ref %p", p);
ep->ref[n] = p;
}
KASSERT(p == NULL, ("Too many references to event"));
ep->func = func;
ep->arg = arg;
mtx_lock(&g_eventlock);
TSHOLD("GEOM events");
TAILQ_INSERT_TAIL(&g_events, ep, events);
mtx_unlock(&g_eventlock);
wakeup(&g_wait_event);
if (epp != NULL)
*epp = ep;
curthread->td_pflags |= TDP_GEOM;
return (0);
}
int
g_post_event(g_event_t *func, void *arg, int flag, ...)
{
va_list ap;
int i;
KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
("Wrong flag to g_post_event"));
va_start(ap, flag);
i = g_post_event_x(func, arg, flag, 0, NULL, ap);
va_end(ap);
return (i);
}
void
g_do_wither()
{
mtx_lock(&g_eventlock);
g_wither_work = 1;
mtx_unlock(&g_eventlock);
wakeup(&g_wait_event);
}
/*
* XXX: It might actually be useful to call this function with topology held.
* XXX: This would ensure that the event gets created before anything else
* XXX: changes. At present all users have a handle on things in some other
* XXX: way, so this remains an XXX for now.
*/
int
g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
{
va_list ap;
struct g_event *ep;
int error;
g_topology_assert_not();
KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
("Wrong flag to g_post_event"));
va_start(ap, flag);
error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
va_end(ap);
if (error)
return (error);
mtx_lock(&g_eventlock);
while (!(ep->flag & EV_DONE))
msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
if (ep->flag & EV_CANCELED)
error = EAGAIN;
mtx_unlock(&g_eventlock);
g_free(ep);
return (error);
}
void
g_event_init()
{
mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
}